將字符串格式化為特定格式

Question

目前我有一個9字符串數字

String s = 123456789

我如何將這個字符串轉換成這種格式？

String newS = 12 - 34 - 5678 - 9

Answer 1

我希望這能幫到您。

public static String formatString(String str) {
    return str.substring(0, 1) + " - " + str.substring(2, 3) + " - " + str.substring(4, 7) + " - " + str.substring(8);
}

Answer 2

使用Java8流，您可以獲得更干凈的版本...

String s = "123456789";

AtomicInteger pos = new AtomicInteger();
String newS = IntStream.of(2, 2, 4, 1)
      .mapToObj(n -> s.substring(pos.getAndAdd(n), pos.get()))
      .collect(Collectors.joining(" - "));

Answer 3

您可以使用正則表達式：

    String s = "123456789";
    Pattern pattern = Pattern.compile("(\\d{2})(\\d{2})(\\d{4})(\\d)");
    Matcher matcher = pattern.matcher(s);
    String formatted = matcher.find() ?
            matcher.group(1) + " - " + matcher.group(2) + " - " + matcher.group(3) + " - " + matcher.group(4) :
            "";
    System.out.println(formatted); // 12 - 34 - 5678 - 9